Method of making alkylene glycols

ABSTRACT

Herein disclosed is a method of hydrating an alkylene oxide that includes introducing an alkylene oxide into water to form a first stream; flowing the first stream through a high shear device to produce a second stream; and contacting the second stream with a catalyst in a reactor to hydrate the alkylene oxide and form an alkylene glycol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/723,221, filed Mar. 12, 2010 (now U.S. Pat. No. 8,304,584, issuedNov. 6, 2012). This application is a continuation-in-part of U.S. patentapplication Ser. No. 12/335,272, filed Dec. 15, 2008 (now U.S. Pat. No.7,910,069, issued Mar. 22, 2011), which is a divisional application ofU.S. patent application Ser. No. 12/142,443, filed Jun. 19, 2008 (nowU.S. Pat. No. 7,491,856, issued Feb. 17, 2009), which claims the benefitunder 35 U.S.C. §119(e) of U.S. Provisional Patent Application No.60/946,484, filed Jun. 27, 2007. The disclosure of each of theaforementioned applications is hereby incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND

1. Field of the Invention

This invention relates generally to the field of chemical reactions.More specifically, the invention relates to methods of making alkyleneglycols incorporating high shear mixing.

2. Background of the Invention

Ethylene glycol is used as antifreeze in cooling and heating systems, inhydraulic brake fluids, as an industrial humectant, as an ingredient ofelectrolytic condensers, as a solvent in the paint and plasticsindustries, in the formulations of printers' inks, stamp pad inks, andinks for ballpoint pens, as a softening agent for cellophane, and in thesynthesis of safety explosives, plasticizers, synthetic fibers(TERYLENE®, DACRON®), and synthetic waxes. Ethylene glycol is also usedto de-ice airport runways and aircraft. Plainly, ethylene glycol is anindustrially important compound with many applications.

Prior methods for hydrating alkylene oxides to the alkylene glycolsinclude the direct hydration reaction without benefit of catalyst andthe catalytic hydration of alkylene oxides using mineral acid catalysts.These mineral acid catalytic reactions are homogeneous thereby posing aproblem for the commercial production of glycols since the catalyst iscarried over into the product and must be separated. Present commercialprocesses use a noncatalytic hydration procedure which must use largeratios of water to alkylene oxide thereby presenting a problem ofseparation of the water from the finished product. This separationconsumes large amounts of energy which recently has been the cause ofmuch concern.

Recently, attempts have been made to discover a new catalyst for thehydration of alkylene oxides to the respective glycols. For example,other catalytic processes use tetramethyl ammonium iodide and tetraethylammonium bromide, or organic tertiary amines such as triethylamine andpyrridine. Despite a focus on the catalyst technology, little has beendone toward improving the mixing of the alkylene oxide with the waterphase to optimize the reaction.

Consequently, there is a need for accelerated methods for making alkylglycols by improving the mixing of ethylene oxide into the water phase.

SUMMARY

Herein disclosed is a method of hydrating an alkylene oxide. In anembodiment, the method comprises (a) introducing an alkylene oxide intowater to form a first stream; (b) flowing the first stream through ahigh shear device to produce a second stream; and (c) contacting thesecond stream with a catalyst in a reactor to hydrate the alkylene oxideand form an alkylene glycol. In some embodiments, alkylene oxidecomprises ethylene oxide, propylene oxide, butylene oxide, orcombinations thereof. In some embodiments, step (b) of the methodcomprises subjecting the first stream to high shear mixing at a tipspeed of at least about 23 m/sec. In some embodiments, step (b) of themethod comprises subjecting the first stream to a shear rate of greaterthan about 20,000 s⁻¹. In some embodiments, producing the second streamcomprises an energy expenditure of at least about 1000 W/m³. In someembodiments, the catalyst comprises an amine, an acid catalyst, anorganometallic compound, an alkali metal halide, a quaternary ammoniumhalide, zeolites, or combinations thereof. In some embodiments, thealkylene glycol comprises ethylene glycol.

Also disclosed herein is a method of hydrating an alkylene oxide. Themethod comprises (a) introducing an alkylene oxide into water to form afirst stream; (b) passing the first stream through a high shear deviceto hydrate the alkylene oxide to produce a second stream comprising analkylene glycol; and (c) recovering the alkylene glycol from the secondstream. In some embodiments, the high shear device comprises a catalyticsurface.

A method of producing polyethylene glycol is described in thisdisclosure. The method comprises introducing ethylene oxide and water orethylene glycol or ethylene glycol oligomer into a high shear device toproduce a first stream; and subjecting the first stream to a catalystthat promotes the formation of polyethylene glycol. In some embodiments,the high shear device comprises a catalytic surface that promotes theformation of polyethylene glycol.

Furthermore, a system for hydrating an alkylene oxide is disclosed. Thesystem comprises at least one high shear device configured to form amixed stream of an alkylene oxide and water comprising a rotor and astator, the rotor and the stator are separated by a shear gap in therange of from about 0.02 mm to about 5 mm, wherein the shear gap is aminimum distance between the rotor and the stator, and wherein the highshear device is capable of producing a tip speed of the at least onerotor of greater than about 23 m/s (4,500 ft/min); a pump configured fordelivering a liquid stream to the high shear device; and a reactor forhydrating the alkylene oxide coupled to the high shear device, thereactor is configured for receiving the mixed stream from the high sheardevice. In some embodiments, the high shear device comprises two or morerotors and two or more stators. In some embodiments, the high sheardevice comprises a rotor tip and the device is configured for operatingat a flow rate of at least 300 L/h at a tip speed of at least about 23m/sec. In some embodiments, the high shear device is configured toprovide an energy expenditure greater than about 1000 W/m³. In someembodiments, the system further comprises more than one high sheardevice. In some embodiments, the high shear device has a tip speed ofgreater than about 20 m/s (4000 ft/min). In some embodiments, the systemfurther comprises a fixed bed reactor, the reactor comprising ahydration catalyst. In some embodiments, the high shear device comprisesat least two generators. In some embodiments, the high shear devicecomprises a catalytic surface.

Furthermore, embodiments disclosed herein pertain to a method ofhydrating an alkylene oxide that may include introducing an alkyleneoxide into water to form a first stream; flowing the first streamthrough a high shear device to produce a second stream; and contactingthe second stream with a catalyst in a reactor to hydrate the alkyleneoxide and form an alkylene glycol. The method may include operating thehigh shear device at a tip speed of at least about 23 m/sec. the methodmay include operating the high shear device at a shear rate of greaterthan about 20,000 s⁻¹.

The alkylene oxide may be, for example, ethylene oxide, propylene oxide,butylene oxide, or combinations thereof. Producing the second stream mayentail an energy expenditure of at least about 1000 W/m³. The catalystmay include an amine, an acid catalyst, an organometallic compound, analkali metal halide, a quaternary ammonium halide, zeolites, orcombinations thereof. The alkylene glycol comprises may include glycol.

Further embodiments of the disclosure pertain to a method of hydratingan alkylene oxide that may include introducing an alkylene oxide intowater to form a first stream; flowing the first stream through a highshear device to produce a second stream; and contacting the secondstream with a catalyst in a reactor. The method may also includerecovering the alkylene glycol from the second stream. The method mayalso include operating the high shear device at a shear rate in therange of about 20,000 s⁻¹ to about 1,600,000 s⁻¹.

In aspects, in the reactor the alkylene oxide may be hydrated to form analkylene glycol. The high shear device may include a catalytic surface.In other aspects, in the reactor the alkyline oxide may be hydrated toform ethylene glycol. The reactor may be a fixed bed reactor. Thecatalyst may be a hydration catalyst.

Other embodiments disclosed herein pertain to a method of producingpolyethylene glycol that may include introducing a first componentcomprising ethylene oxide and a second component selected from the groupconsisting of water, ethylene glycol, and ethylene glycol oligomer, intoa high shear device to produce a first stream; and reacting at least aportion of the first stream with a catalyst to produce polyethyleneglycol. The method may further include operating the high shear deviceat a shear rate in the range of about 20,000 s⁻¹ to about 1,600,000 s⁻¹.

In aspects reacting step may occur in a fixed bed reactor. In otheraspects, the high shear device may include a catalytic surface. In yetother aspects, the high shear device may include a catalytic surfacethat promotes formation of additional polyethylene glycol.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter that form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand the specific embodiments disclosed may be readily utilized as abasis for modifying or designing other structures for carrying out thesame purposes of the present invention. It should also be realized bythose skilled in the art that such equivalent constructions do notdepart from the spirit and scope of the invention as set forth in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of theinvention, reference will now be made to the accompanying drawings inwhich:

FIG. 1 is a process flow diagram of a process for the hydration of analkylene oxide with water in liquid phase, according to certainembodiments of the invention; and

FIG. 2 is a longitudinal cross-section view of a multi-stage high sheardevice, as employed in an embodiment of the system of FIG. 1.

NOTATION AND NOMENCLATURE

The term “catalytic surface” is used herein to refer to a surface in adevice that is constructed with catalytic material (such as metals,alloys, etc.) so that catalytic activity is manifested when suitablesubstance comes in touch with said catalytic surface. The use of theterm “catalytic surface” in this document includes all such surfacesregardless of the shape and size of surface, material of construct,method of make, degree of activity, or purpose of use.

Certain terms are used throughout the following description and claimsto refer to particular system components. This document does not intendto distinguish between components that differ in name but not function.In the following discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . ”.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Methods and systems for preparing alkylene glycols are described herein.The methods and systems incorporate the novel use of a high shear deviceto promote dispersion and solubility of an alkylene oxide in water. Thehigh shear device may allow for lower reaction temperatures andpressures and may also reduce reaction time. Further advantages andaspects of the disclosed methods and system are described below.

In an embodiment, a method of making an alkylene glycol comprisesintroducing an alkylene oxide gas into a liquid water stream to form agas-liquid stream. The method further comprises flowing the gas-liquidstream through a high shear device so as to form a dispersion with gasbubbles having a mean diameter less than about 1 micron. In addition themethod comprises contacting the gas-liquid stream with a catalyst in areactor to hydrate the alkylene oxide and form the alkylene glycol.

In an embodiment, a system for making an alkylene glycol comprises atleast one high shear device configured to form a dispersion of analkylene oxide and water. The high shear device comprises a rotor and astator. The rotor and the stator are separated by a shear gap in therange of from about 0.02 mm to about 5 mm. The shear gap is a minimumdistance between the rotor and the stator. The high shear device iscapable of producing a tip speed of the at least one rotor of greaterthan about 23 m/s (4,500 ft/min). In addition, the system comprises apump configured for delivering a liquid stream comprising liquid phaseto the high shear device. The system also comprises a reactor forhydrating the alkylene oxide coupled to said high shear device. Thereactor is configured for receiving the dispersion from the high sheardevice.

The disclosed methods and systems for the hydration of alkylene oxidesemploy a high shear mechanical device to provide rapid contact andmixing of the alkylene oxide gas and water in a controlled environmentin the reactor/mixer device. The term “alkylene oxide gas” as usedherein includes both substantially pure alkylene oxides as well asgaseous mixtures containing alkylene oxides. In particular, embodimentsof the systems and methods may be used in the production of alkyleneglycols from the hydration of alkylene oxides. Preferably, the methodcomprises a heterogeneous phase reaction of liquid water with analkylene oxide gas. The high shear device reduces the mass transferlimitations on the reaction and thus increases the overall reactionrate. Furthermore, in some embodiments, liquid alkylene oxides areintroduced into the high shear mechanical device to be intimately mixedwith water for the hydration reactions of alkylene oxides.

Chemical reactions involving liquids, gases and solids rely on time,temperature, and pressure to define the rate of reactions. In caseswhere it is desirable to react two or more raw materials of differentphases (e.g. solid and liquid; liquid and gas; solid, liquid and gas),one of the limiting factors in controlling the rate of reaction involvesthe contact time of the reactants. In the case of heterogeneouslycatalyzed reactions there is the additional rate limiting factor ofhaving the reacted products removed from the surface of the catalyst toenable the catalyst to catalyze further reactants. Contact time for thereactants and/or catalyst is often controlled by mixing which providescontact with two or more reactants involved in a chemical reaction. Areactor assembly that comprises an external high shear device or mixeras described herein makes possible decreased mass transfer limitationsand thereby allows the reaction to more closely approach kineticlimitations. When reaction rates are accelerated, residence times may bedecreased, thereby increasing obtainable throughput. Product yield maybe increased as a result of the high shear system and process.Alternatively, if the product yield of an existing process isacceptable, decreasing the required residence time by incorporation ofsuitable high shear may allow for the use of lower temperatures and/orpressures than conventional processes.

System for Hydration Alkylene Oxides

A high shear alkylene oxide hydration system will now be described inrelation to FIG. 1, which is a process flow diagram of an embodiment ofa high shear system 100 for the production of alkylene glycols via thehydration of alkylene oxides. The basic components of a representativesystem include external high shear device (HSD) 140, vessel 110, andpump 105. As shown in FIG. 1, the high shear device may be locatedexternal to vessel/reactor 110. Each of these components is furtherdescribed in more detail below. Line 121 is connected to pump 105 forintroducing either an alkylene oxide reactant. Line 113 connects pump105 to HSD 140, and line 118 connects HSD 140 to vessel 110. Line 122 isconnected to line 113 for introducing an alkylene oxide gas. Line 117 isconnected to vessel 110 for removal of unreacted alkylene oxides, andother reaction gases. Additional components or process steps may beincorporated between vessel 110 and HSD 140, or ahead of pump 105 or HSD140, if desired. High shear devices (HSD) such as a high shear, or highshear mill, are generally divided into classes based upon their abilityto mix fluids. Mixing is the process of reducing the size ofinhomogeneous species or particles within the fluid. One metric for thedegree or thoroughness of mixing is the energy density per unit volumethat the mixing device generates to disrupt the fluid particles. Theclasses are distinguished based on delivered energy density. There arethree classes of industrial mixers having sufficient energy density toconsistently produce mixtures or emulsions with particle or bubble sizesin the range of 0 to 50 microns. High shear mechanical devices includehomogenizers as well as colloid mills.

High shear devices (HSD) such as a high shear, or high shear mill, aregenerally divided into classes based upon their ability to mix fluids.Mixing is the process of reducing the size of inhomogeneous species orparticles within the fluid. One metric for the degree or thoroughness ofmixing is the energy density per unit volume that the mixing devicegenerates to disrupt the fluid particles. The classes are distinguishedbased on delivered energy density. There are three classes of industrialmixers having sufficient energy density to consistently produce mixturesor emulsions with particle or bubble sizes in the range of 0 to 50 μm.

Homogenization valve systems are typically classified as high energydevices. Fluid to be processed is pumped under very high pressurethrough a narrow-gap valve into a lower pressure environment. Thepressure gradients across the valve and the resulting turbulence andcavitations act to break-up any particles in the fluid. These valvesystems are most commonly used in milk homogenization and can yieldaverage particle size range from about 0.01 μm to about 1 μm. At theother end of the spectrum are high shear systems classified as lowenergy devices. These systems usually have paddles or fluid rotors thatturn at high speed in a reservoir of fluid to be processed, which inmany of the more common applications is a food product. These systemsare usually used when average particle, or bubble, sizes of greater than20 microns are acceptable in the processed fluid.

Between low energy—high shears and homogenization valve systems, interms of the mixing energy density delivered to the fluid, are colloidmills, which are classified as intermediate energy devices. The typicalcolloid mill configuration includes a conical or disk rotor that isseparated from a complementary, liquid-cooled stator by aclosely-controlled rotor-stator gap, which is maybe between 0.025 mm and10.0 mm. Rotors are usually driven by an electric motor through a directdrive or belt mechanism. Many colloid mills, with proper adjustment, canachieve average particle, or bubble, sizes of about 0.01 μm to about 25μm in the processed fluid. These capabilities render colloid millsappropriate for a variety of applications including colloid andoil/water-based emulsion processing such as that required for cosmetics,mayonnaise, silicone/silver amalgam formation, or roofing-tar mixing.

An approximation of energy input into the fluid (kW/L/min) can be madeby measuring the motor energy (kW) and fluid output (L/min). Inembodiments, the energy expenditure of a high shear device is greaterthan 1000 W/m³. In embodiments, the energy expenditure is in the rangeof from about 3000 W/m³ to about 7500 W/m³. The shear rate generated ina high shear device may be greater than 20,000 s⁻¹. In embodiments, theshear rate generated is in the range of from 20,000 s⁻¹ to 100,000 s⁻¹.

Tip speed is the velocity (m/sec) associated with the end of one or morerevolving elements that is transmitting energy to the reactants. Tipspeed, for a rotating element, is the circumferential distance traveledby the tip of the rotor per unit of time, and is generally defined bythe equation V (m/sec)=π·D·n, where V is the tip speed, D is thediameter of the rotor, in meters, and n is the rotational speed of therotor, in revolutions per second. Tip speed is thus a function of therotor diameter and the rotation rate. Also, tip speed may be calculatedby multiplying the circumferential distance transcribed by the rotortip, 2πR, where R is the radius of the rotor (meters, for example) timesthe frequency of revolution (for example revolutions (meters, forexample) times the frequency of revolution (for example revolutions perminute, rpm).

For colloid mills, typical tip speeds are in excess of 23 m/sec (4500ft/min) and can exceed 40 m/sec (7900 ft/min). For the purpose of thepresent disclosure the term ‘high shear’ refers to mechanicalrotor-stator devices, such as mills or mixers, that are capable of tipspeeds in excess of 5 m/sec (1000 ft/min) and require an externalmechanically driven power device to drive energy into the stream ofproducts to be reacted. A high shear device combines high tip speedswith a very small shear gap to produce significant friction on thematerial being processed. Accordingly, a local pressure in the range ofabout 1000 MPa (about 145,000 psi) to about 1050 MPa (152,300 psi) andelevated temperatures at the tip of the shear mixer are produced duringoperation. In certain embodiments, the local pressure is at least about1034 MPa (about 150,000 psi).

Referring now to FIG. 1, there is presented a schematic diagram of ahigh shear device 200. High shear device 200 comprises at least onerotor-stator combination. The rotor-stator combinations may also beknown as generators 220, 230, 240 or stages without limitation. The highshear device 200 comprises at least two generators, and most preferably,the high shear device comprises at least three generators.

The first generator 220 comprises rotor 222 and stator 227. The secondgenerator 230 comprises rotor 223, and stator 228; the third generatorcomprises rotor 224 and stator 229. For each generator 220, 230, 240 therotor is rotatably driven by input 250. The generators 220, 230, 240rotate about axis 260 in rotational direction 265. Stator 227 is fixablycoupled to the high shear device wall 255.

The generators include gaps between the rotor and the stator. The firstgenerator 220 comprises a first gap 225; the second generator 230comprises a second gap 235; and the third generator 240 comprises athird gap 245. The gaps 225, 235, 245 are between about 0.025 mm (0.01in) and 10.0 mm (0.4 in) wide. Alternatively, the process comprisesutilization of a high shear device 200 wherein the gaps 225, 235, 245are between about 0.5 mm (0.02 in) and about 2.5 mm (0.1 in). In certaininstances the gap is maintained at about 1.5 mm (0.06 in).Alternatively, the gaps 225, 235, 245 are different between generators220, 230, 240. In certain instances, the gap 225 for the first generator220 is greater than about the gap 235 for the second generator 230,which is greater than about the gap 245 for the third generator 240.

Additionally, the width of the gaps 225, 235, 245 may comprise a coarse,medium, fine, and super-fine characterization. Rotors 222, 223, and 224and stators 227, 228, and 229 may be toothed designs. Each generator maycomprise two or more sets of rotor-stator teeth, as known in the art.Rotors 222, 223, and 224 may comprise a number of rotor teethcircumferentially spaced about the circumference of each rotor. Stators227, 228, and 229 may comprise a number of stator teethcircumferentially spaced about the circumference of each stator. Therotor and the stator may be of any suitable size. In one embodiment, theinner diameter of the rotor is about 64 mm and the outer diameter of thestator is about 60 mm. In other embodiments, the inner diameter of therotor is about 11.8 cm and the outer diameter of the stator is about15.4 cm. In further embodiments, the rotor and stator may have alternatediameters in order to alter the tip speed and shear pressures. Incertain embodiments, each of three stages is operated with a super-finegenerator, comprising a gap of between about 0.025 mm and about 3 mm.When a feed stream 205 including solid particles is to be sent throughhigh shear device 200, the appropriate gap width is first selected foran appropriate reduction in particle size and increase in particlesurface area. In embodiments, this is beneficial for increasing catalystsurface area by shearing and dispersing the particles.

High shear device 200 is fed a reaction mixture comprising the feedstream 205. Feed stream 205 comprises an emulsion of the dispersiblephase and the continuous phase. Emulsion refers to a liquefied mixturethat contains two distinguishable substances (or phases) that will notreadily mix and dissolve together. Most emulsions have a continuousphase (or matrix), which holds therein discontinuous droplets, bubbles,and/or particles of the other phase or substance. Emulsions may behighly viscous, such as slurries or pastes, or may be foams, with tinygas bubbles suspended in a liquid. As used herein, the term “emulsion”encompasses continuous phases comprising gas bubbles, continuous phasescomprising particles (e.g., solid catalyst), continuous phasescomprising droplets of a fluid that is substantially insoluble in thecontinuous phase, and combinations thereof.

Feed stream 205 may include a particulate solid catalyst component. Feedstream 205 is pumped through the generators 220, 230, 240, such thatproduct dispersion 210 is formed. In each generator, the rotors 222,223, 224 rotate at high speed relative to the fixed stators 227, 228,229. The rotation of the rotors pumps fluid, such as the feed stream205, between the outer surface of the rotor 222 and the inner surface ofthe stator 227 creating a localized high shear condition. The gaps 225,235, 245 generate high shear forces that process the feed stream 205.The high shear forces between the rotor and stator functions to processthe feed stream 205 to create the product dispersion 210. Each generator220, 230, 240 of the high shear device 200 has interchangeablerotor-stator combinations for producing a narrow distribution of thedesired bubble size, if feedstream 205 comprises a gas, or globule size,if feedstream 205 comprises a liquid, in the product dispersion 210.

The product dispersion 210 of gas particles, or bubbles, in a liquidcomprises an emulsion. In embodiments, the product dispersion 210 maycomprise a dispersion of a previously immiscible or insoluble gas,liquid or solid into the continuous phase. The product dispersion 210has an average gas particle, or bubble, size less than about 1.5 μm;preferably the bubbles are sub-micron in diameter. In certain instances,the average bubble size is in the range from about 1.0 μm to about 0.1μm. Alternatively, the average bubble size is less than about 400 nm(0.4 μm) and most preferably less than about 100 nm (0.1 μm).

The high shear device 200 produces a gas emulsion capable of remainingdispersed at atmospheric pressure for at least about 15 minutes. For thepurpose of this disclosure, an emulsion of gas particles, or bubbles, inthe dispersed phase in product dispersion 210 that are less than 1.5 μmin diameter may comprise a micro-foam. Not to be limited by a specifictheory, it is known in emulsion chemistry that sub-micron particles, orbubbles, dispersed in a liquid undergo movement primarily throughBrownian motion effects. The bubbles in the emulsion of productdispersion 210 created by the high shear device 200 may have greatermobility through boundary layers of solid catalyst particles, therebyfacilitating and accelerating the catalytic reaction through enhancedtransport of reactants.

The rotor is set to rotate at a speed commensurate with the diameter ofthe rotor and the desired tip speed as described hereinabove. Transportresistance is reduced by incorporation of high shear device 200 suchthat the velocity of the reaction is increased by at least about 5%.Alternatively, the high shear device 200 comprises a high shear colloidmill that serves as an accelerated rate reactor (ARR). The acceleratedrate reactor comprises a single stage dispersing chamber. Theaccelerated rate reactor comprises a multiple stage inline dispersercomprising at least 2 stages.

Selection of the high shear device 200 is dependent on throughputrequirements and desired particle or bubble size in the outletdispersion 210. In certain instances, high shear device 200 comprises aDispax Reactor® of IKA® Works, Inc., Wilmington, N.C. and APV NorthAmerica, Inc., Wilmington, Mass. Model DR 2000/4, for example, comprisesa belt drive, 4M generator, PTFE sealing ring, inlet flange 1″ sanitaryclamp, outlet flange ¾″ sanitary clamp, 2 HP power, output speed of 7900rpm, flow capacity (water) approximately 300 l/h to approximately 700l/h (depending on generator), a tip speed of from 9.4 m/s to about 41m/s (about 1850 ft/min to about 8070 ft/min). Several alternative modelsare available having various inlet/outlet connections, horsepower,nominal tip speeds, output rpm, and nominal flow rate.

Without wishing to be limited to a particular theory, it is believedthat the level or degree of high shear is sufficient to increase ratesof mass transfer and may also produce localized non-ideal conditionsthat enable reactions to occur that would not otherwise be expected tooccur based on Gibbs free energy predictions. Localized non idealconditions are believed to occur within the high shear device resultingin increased temperatures and pressures with the most significantincrease believed to be in localized pressures. The increase inpressures and temperatures within the high shear device areinstantaneous and localized and quickly revert back to bulk or averagesystem conditions once exiting the high shear device. In some cases, thehigh shear device induces cavitation of sufficient intensity todissociate one or more of the reactants into free radicals, which mayintensify a chemical reaction or allow a reaction to take place at lessstringent conditions than might otherwise be required. Cavitation mayalso increase rates of transport processes by producing local turbulenceand liquid micro-circulation (acoustic streaming).

Vessel

Vessel or reactor 110 is any type of vessel in which a multiphasereaction can be propagated to carry out the above-described conversionreaction(s). For instance, a continuous or semi-continuous stirred tankreactor, or one or more batch reactors may be employed in series or inparallel. In some applications vessel 110 may be a tower reactor, and inothers a tubular reactor or multi-tubular reactor. A catalyst inlet line115 may be connected to vessel 110 for receiving a catalyst solution orslurry during operation of the system.

Vessel 110 may include one or more of the following components: stirringsystem, heating and/or cooling capabilities, pressure measurementinstrumentation, temperature measurement instrumentation, one or moreinjection points, and level regulator (not shown), as are known in theart of reaction vessel design. For example, a stirring system mayinclude a motor driven mixer. A heating and/or cooling apparatus maycomprise, for example, a heat exchanger. Alternatively, as much of theconversion reaction may occur within HSD 140 in some embodiments, vessel110 may serve primarily as a storage vessel in some cases. Althoughgenerally less desired, in some applications vessel 110 may be omitted,particularly if multiple high shears/reactors are employed in series, asfurther described below.

Heat Transfer Devices

In addition to the above-mentioned heating/cooling capabilities ofvessel 110, other external or internal heat transfer devices for heatingor cooling a process stream are also contemplated in variations of theembodiments illustrated in FIG. 1. Some suitable locations for one ormore such heat transfer devices are between pump 105 and HSD 140,between HSD 140 and vessel 110, and between vessel 110 and pump 105 whensystem 1 is operated in multi-pass mode. Some non-limiting examples ofsuch heat transfer devices are shell, tube, plate, and coil heatexchangers, as are known in the art.

Pumps

Pump 105 is configured for either continuous or semi-continuousoperation, and may be any suitable pumping device that is capable ofproviding greater than 2 atm pressure, preferably greater than 3 atmpressure, to allow controlled flow through HSD 140 and system 1. Forexample, a Roper Type 1 gear pump, Roper Pump Company (Commerce, Ga.)Dayton Pressure Booster Pump Model 2P372E, Dayton Electric Co. (Niles,Ill.) is one suitable pump. Preferably, all contact parts of the pumpcomprise stainless steel. In some embodiments of the system, pump 105 iscapable of pressures greater than about 20 atm. In addition to pump 105,one or more additional, high pressure pump (not shown) may be includedin the system illustrated in FIG. 1. For example, a booster pump, whichmay be similar to pump 105, may be included between HSD 140 and vessel110 for boosting the pressure into vessel 110. As another example, asupplemental feed pump, which may be similar to pump 105, may beincluded for introducing additional reactants or catalyst into vessel110.

Hydration of Alkylene Oxides

In operation for the catalytic hydration of alkylene oxides,respectively, a dispersible alkylene oxide gas stream is introduced intosystem 100 via line 122, and combined in line 113 with a water stream toform a gas-liquid stream. Alternatively, the alkylene oxide gas may befed directly into HSD 140, instead of being combined with the liquidreactant (i.e., water) in line 113. Pump 105 is operated to pump theliquid reactant (water) through line 121, and to build pressure and feedHSD 140, providing a controlled flow throughout high shear (HSD) 140 andhigh shear system 100.

In a preferred embodiment, alkylene oxide gas may continuously be fedinto the water stream 112 to form high shear feed stream 113 (e.g. agas-liquid stream). In high shear device 140, water and the alkyleneoxide vapor are highly dispersed such that nanobubbles and/ormicrobubbles of alkylene oxide are formed for superior dissolution ofalkylene oxide vapor into solution. Once dispersed, the dispersion mayexit high shear device 140 at high shear outlet line 118. Stream 118 mayoptionally enter fluidized or fixed bed 142 in lieu of a slurry catalystprocess. However, in a slurry catalyst embodiment, high shear outletstream 118 may directly enter hydration reactor 110 for hydration. Thereaction stream may be maintained at the specified reaction temperature,using cooling coils in the reactor 110 to maintain reaction temperature.Hydration products (e.g. alkylene glycols) may be withdrawn at productstream 116.

In an exemplary embodiment, the high shear device comprises a commercialdisperser such as IKA® model DR 2000/4, a high shear, three stagedispersing device configured with three rotors in combination withstators, aligned in series. The disperser is used to create thedispersion of alkylene oxides in the liquid medium comprising water(i.e., “the reactants”). The rotor/stator sets may be configured asillustrated in FIG. 2, for example. The combined reactants enter thehigh shear device via line 113 and enter a first stage rotor/statorcombination having circumferentially spaced first stage shear openings.The coarse dispersion exiting the first stage enters the secondrotor/stator stage, which has second stage shear openings. The reducedbubble-size dispersion emerging from the second stage enters the thirdstage rotor/stator combination having third stage shear openings. Thedispersion exits the high shear device via line 118. In someembodiments, the shear rate increases stepwise longitudinally along thedirection of the flow. For example, in some embodiments, the shear ratein the first rotor/stator stage is greater than the shear rate insubsequent stage(s). In other embodiments, the shear rate issubstantially constant along the direction of the flow, with the stageor stages being the same. If the high shear device includes a PTFE seal,for example, the seal may be cooled using any suitable technique that isknown in the art. For example, the reactant stream flowing in line 113may be used to cool the seal and in so doing be preheated as desiredprior to entering the high shear device.

The rotor of HSD 140 is set to rotate at a speed commensurate with thediameter of the rotor and the desired tip speed. As described above, thehigh shear device (e.g., colloid mill) has either a fixed clearancebetween the stator and rotor or has adjustable clearance. HSD 140 servesto intimately mix the alkylene oxide vapor and the reactant liquid(i.e., water). In some embodiments of the process, the transportresistance of the reactants is reduced by operation of the high sheardevice such that the velocity of the reaction (i.e. reaction rate) isincreased by greater than a factor of about 5. In some embodiments, thevelocity of the reaction is increased by at least a factor of 10. Insome embodiments, the velocity is increased by a factor in the range ofabout 10 to about 100 fold. In some embodiments, HSD 140 delivers atleast 300 L/h with a power consumption of 1.5 kW at a nominal tip speedof at least 4500 ft/min, and which may exceed 7900 ft/min (140 m/sec).Although measurement of instantaneous temperature and pressure at thetip of a rotating shear unit or revolving element in HSD 140 isdifficult, it is estimated that the localized temperature seen by theintimately mixed reactants may be in excess of 500° C. and at pressuresin excess of 500 kg/cm² under high shear conditions. The high shearresults in dispersion of the alkylene oxide gas in micron orsubmicron-sized bubbles. In some embodiments, the resultant dispersionhas an average bubble size less than about 1.5 μm. Accordingly, thedispersion exiting HSD 140 via line 118 comprises micron and/orsubmicron-sized gas bubbles. In some embodiments, the mean bubble sizeis in the range of about 0.4 μm to about 1.5 μm. In some embodiments,the mean bubble size is less than about 400 nm, and may be about 100 nmin some cases. In many embodiments, the microbubble dispersion is ableto remain dispersed at atmospheric pressure for at least 15 minutes.

Once dispersed, the resulting alkylene oxide/water dispersion exits HSD140 via line 118 and feeds into vessel 110, as illustrated in FIG. 1. Asa result of the intimate mixing of the reactants prior to enteringvessel 110, a significant portion of the chemical reaction may takeplace in HSD 140, with or without the presence of a catalyst.Accordingly, in some embodiments, reactor/vessel 110 may be usedprimarily for heating and separation of volatile reaction products fromthe alkylene glycol product. Alternatively, or additionally, vessel 110may serve as a primary reaction vessel where most of the alkylene glycolproduct is produced. Vessel/reactor 110 may be operated in eithercontinuous or semi-continuous flow mode, or it may be operated in batchmode. The contents of vessel 110 may be maintained at a specifiedreaction temperature using heating and/or cooling capabilities (e.g.,cooling coils) and temperature measurement instrumentation. Pressure inthe vessel may be monitored using suitable pressure measurementinstrumentation, and the level of reactants in the vessel may becontrolled using a level regulator (not shown), employing techniquesthat are known to those of skill in the art. The contents are stirredcontinuously or semi-continuously.

Commonly known hydration reaction conditions may suitably be employed asthe conditions of the production of an alkylene glycol by hydratingalkylene oxides by using catalysts. There is no particular restrictionas to the reaction conditions. For exemplary purposes, the method willbe discussed with respect to ethylene glycol. However, it is envisionedthat embodiments of the method may be used to produce any alkyleneglycol. In the production of ethylene glycol, theoretically one mole ofwater is required to hydrate one mole of ethylene oxide. Actually,however, greater than equal molecular proportions of water to ethyleneoxide are required for good results. Although a conversion ofapproximately 90% can sometimes be obtained when employing a reactantratio of water to ethylene oxide of around 2, reactant ratios of greaterthan 6 are generally required to achieve reasonably high yields ofproducts, otherwise the ethylene glycol formed reacts with ethyleneoxide to form di- and triethylene glycols. The effects of the reactantratios on the results obtained for the production of ethylene glycol andother alkylene glycols are well known. In reacting steam and ethyleneoxide in a ratio of at least 17:1 over a stationary bed of the claimedcatalyst, yields based on the ethylene oxide consumed are found to bereasonably high.

The primary by-products of the hydrolysis reaction are di- andpolyglycols, e.g., dialkylene glycol, trialkylene glycol andtetra-alkylene glycol. The formation of the di- and polyglycols isbelieved to be primarily due to the reaction of alkylene oxide withalkylene glycol. As alkylene oxides are generally more reactive withalkylene glycols than they are with water, large excesses of water areemployed in order to favor the reaction with water and thereby obtain acommercially-attractive selectivity to the monoglycol product.

The reaction temperature, which varies depending upon the type of thestarting alkylene oxide, the type of the catalyst, the composition ofthe reactant mixture at the early stage of the reaction, etc., isgenerally 50° C. to 200° C., preferably 110° C. to 160° C. The reactionpressure, which varies according to reaction temperature, and the extentof advance of the reaction, is generally 3 to 50 kg/cm². If desired, thepressure within the reactor may be adjusted occasionally. The reactiontime may be about 30 minutes to about 3 hours. The contacting time ofthe reactants over a catalyst can vary anywhere from period of less thana second to periods ranging up to 25 seconds.

The alkylene oxides for the reaction may be used alone or in combinationas a mixture of different types. The alkylene oxides can have anystructure, such as, aliphatic, aromatic, heteroaromatic,aliphatic-aromatic or aliphatic-heteroaromatic. They can also containother functional groups, and it should be determined beforehand whetherthese functional groups should remain unchanged or should be hydratedthemselves.

Embodiments of the disclosed process may be suitable for hydratingstraight or branched alkylene oxides. Example of alkylene oxides includewithout limitation, ethylene oxide, butylenes oxide, propylene oxide,and the like. The alkylene oxide may have from 2 to 4 carbon atoms.

In an embodiment, liquid alkylene oxide is used as feed in the hydrationreaction. For example, ethylene oxide (EO) is introduced into the HSDunit as a liquid. Due to the cavitation conditions created by highshear, alkylene oxide may form small gas bubbles (diameter less than 1micron) dispersed in the liquid phase or alkylene oxide may remainliquid and become intimately mixed with water for the hydration reactionto produce alkylene glycol.

In some embodiments, the hydration reaction takes place in the HSD as athermal conversion reactor. A thermal conversion reactor is a reactorwherein the reaction may be promoted by heat alone and does not requireor contain a catalyst. After the alkylene oxide is converted to itscorresponding alkylene glycol, the effluent from the HSD is sent to adistillation column to separate the alkylene glycol from unreactedreactants (e.g., excess water). The reaction conditions in the HSD(acting as a thermal conversion reactor) are generally in accordancewith those commonly used in thermal alkylene glycol production exceptthat the HSD is able to produce high temperature and high pressure in alocalized manner due to the cavitation effect. Therefore the globaltemperature and pressure may not need to be as severe as required by thehydration reactions. The reaction conditions listed below as examplesare considered to be localized reaction conditions in the HSD. The waterto alkylene oxide ratio is in the range of from 15 to 30 moles of waterper mole of alkylene oxide. The reaction temperature is in the range offrom 150° C. to 250° C. The reaction pressure is in the range of from500 to 5000 kPa.

In some other embodiments, the hydration reaction takes place in avessel that receives the effluent of the HSD, wherein said vesselcontains a suitable catalyst for the hydration reactions of alkyleneoxides. Such a vessel serves as a catalytic conversion reactor. Acatalytic conversion reactor is a reactor comprising a catalyst capableof promoting the conversion of alkylene oxide to alkylene glycol(s). Thecatalytic conversion reaction may be conducted in the presence of carbondioxide. Whether to provide carbon dioxide to the reaction may depend onwhether a catalyst is utilized in the reactor and the type of catalystused. For example, if an anion exchange resin is utilized as a catalystit may be desirable to provide an amount of carbon dioxide to thecatalyst bed. The carbon dioxide may be provided to the catalyticconversion reactor in any convenient manner. The carbon dioxide may, forinstance, be introduced separately and/or with one or more of the feedstreams. Carbon dioxide may be present in the reaction mixture ingaseous form or in the form of carbonic acid or in the form of salts ofcarbonic acid. In some cases, carbon dioxide is present in the reactionmixture in an amount no greater than 0.1 wt %; in some other cases,carbon dioxide is present in the reaction mixture in an amount nogreater than 0.05 wt %; in yet other cases, carbon dioxide is present inthe reaction mixture in an amount no greater than 0.01 wt %, based onthe total amount of reactants in the catalytic conversion reactor.

In some further embodiments, the thermal and catalytic conversionreactors are positioned in a series configuration. For example, as shownin FIG. 1, HSD 140 acts as a thermal conversion reactor and vessel 110serves as a catalytic conversion reactor for the hydration of alkyleneoxides. The effluent 118 from HSD 140 may contain some unreactedreactants (e.g., an alkylene oxide and water) and such residue reactantsmay be reacted in the catalytic conversion reactor 110 to continue toproduce alkylene glycol(s). Additional reactants (e.g., alkylene oxideor water or both) and additives (e.g., carbon dioxide) may be added tovessel 110 via any means known to one skilled in the art (not shown inFIG. 1). Effluent 116 from vessel 110 contains alkylene glycol(s),water, and maybe some unreacted alkylene oxide. In some cases, effluent116 is sent to a distillation column to recover the alkylene glycol(s).In some other cases, effluent 116 is recycled to the HSD 140 for furtherreaction.

In some further embodiments, the thermal and catalytic conversionreactors are positioned in a parallel configuration (not shown). Inother embodiments, the thermal and catalytic conversion reactors arepositioned in a combined series and parallel configuration. Thecatalytic conversion reactor is generally downstream of the thermalconversion reactor in a series configuration. One of ordinary skill inthe art with the aid of this disclosure is able to design variousconfigurations of the thermal and catalytic conversion reactors for thehydration reaction of alkylene oxides; therefore all such configurationsare within the scope of this disclosure.

In some further embodiments, catalyst slurry is introduced into the HSDtogether with an alkylene oxide and water so that the HSD serves as acatalytic conversion reactor facilitated by cavitation effect. In yetsome other embodiments, the HSD comprises a catalytic surface andtherefore functions as a catalytic conversion reactor facilitated by thecavitation effect. The localized high temperature and high pressure inthe HSD cause the catalytic conversion reaction (from alkylene oxide toalkylene glycol) to take place under mild global temperature andpressure conditions. In some cases, the reaction rate and selectivityare improved. In some cases, the molar ratio of water to alkylene oxideis reduced so that the recovery of alkylene glycol is made easier. Insome embodiments, sintered metals, (e.g., INCONEL® alloys, HASTELLOY®materials) are be used to construct at least one surface of the HSD. Forexample, the rotors, stators, and/or other components of the HSD may bemanufactured of refractory materials (e.g. sintered metal). In certainembodiments, the rotor and the stator comprise no teeth, thus forcingthe reactants to flow through pores, for example, of a sinteredmaterial.

Catalyst

If a catalyst is used to promote the hydration reaction, it may beintroduced into the vessel via line 115, as an aqueous or nonaqueousslurry or stream. Alternatively, or additionally, catalyst may be addedelsewhere in the system 100. For example, catalyst slurry may beinjected into line 121. In some embodiments, line 121 may contain aflowing water stream and/or alkylene oxide recycle stream from vessel110.

In embodiments, any catalyst suitable for catalyzing a hydrationreaction may be employed. An inert gas such as nitrogen may be used tofill reactor 110 and purge it of any air and/or oxygen. According to oneembodiment, the catalysts useful in the disclosed process may be acidcatalysts. For example, partially amine-neutralized sulfonic acidcatalysts may be used as the catalyst. These catalysts are heterogeneousand may be described more completely as sulfonic acid-type ion exchangeresins. These resins are then modified by passing sufficient aminethrough the resin to partially neutralize the sulfonic acid groupscontained therein. Primary, secondary or tertiary amines are eachacceptable. Tertiary amines may be used in the disclosed process. Theresult is a catalyst which consists of a mixture of the original freesulfonic acid and the amine salt of the sulfonic acid, all still in theheterogeneous form.

In a specific embodiment, catalyst comprises a styrene-divinylbenzenecopolymer matrix with pendant sulfonic acid groups. Catalysts fallingwithin this species are available from Rohm and Haas under thedesignation Amberlyst™ RTM 15 and Amberlyst™ XN-1010 which differ in theamount of surface area available. Other matrices than thestyrene-divinylbenzene type could be used, including other organicpolymers and inorganic materials, provided only that the substrate becapable of binding the sulfonic acid groups to maintain a heterogeneouscatalyst system.

Other representatives of the numerous acid catalysts that have beensuggested for use in the hydration of alkylene oxides includefluorinated alkyl sulfonic acid ion exchange resins, carboxylic acidsand halogen acids, strong acid cation exchange resins, aliphatic mono-and/or polycarboxylic acids, cationic exchange resins, acidic zeolites,sulfur dioxide, trihalogen acetic acids.

In addition to the acid catalysts, numerous catalysts have beensuggested for the hydration of alkylene oxides. For example, thecatalyst may be an aluminum phosphate catalyst, organic tertiary aminessuch as triethylamine and pyridine, quarternary phosphonium salts,fluoroalkyl sulfonic acid resins, alkali metal halides such aschlorides, bromides and iodides of potassium, sodium and lithium, orquaternary ammonium halides such as tetramethylammonium iodide andtetraethylammonium bromide, or combinations thereof.

Various metal-containing compounds, including metal oxides, may be usedas catalysts for the hydrolysis of alkylene oxides. For example, adehydrating metal oxide such as without limitation, alumina, thoria, oroxides or tungsten, titanium, vanadium, molybdenum or zirconium. Oralternatively alkali metal bases may be used such as alcoholates, oxidesof titanium, tungsten and thorium.

The catalyst may also comprise an organometallic compounds includingmetals such as vanadium, molybdenum, tungsten, titantium, chromium,zirconium, selenium, tellurium, tantalum, rhenium, uranium, orcombinations thereof.

More recently, U.S. Pat. No. 4,277,632, issued Jul. 7, 1981, discloses aprocess for the production of alkylene glycols by the hydrolysis ofalkylene oxides in the presence of a catalyst of at least one memberselected from the group consisting of molybdenum and tungsten. Catalystmay be fed into reactor 110 through catalyst feed stream 115.Alternatively, catalyst may be present in a fixed or fluidized bed 142.

The bulk or global operating temperature of the reactants is desirablymaintained below their flash points. In some embodiments, the operatingconditions of system 100 comprise a temperature in the range of fromabout 50° C. to about 300° C. In specific embodiments, the reactiontemperature in vessel 110, in particular, is in the range of from about90° C. to about 220° C. In some embodiments, the reaction pressure invessel 110 is in the range of from about 5 atm to about 50 atm.

The dispersion may be further processed prior to entering vessel 110 (asindicated by arrow 18), if desired. In vessel 110, alkylene oxidehydration occurs via catalytic hydration. The contents of the vessel arestirred continuously or semi-continuously, the temperature of thereactants is controlled (e.g., using a heat exchanger), and the fluidlevel inside vessel 110 is regulated using standard techniques. Alkyleneoxide hydration may occur either continuously, semi-continuously orbatch wise, as desired for a particular application. Any reaction gasthat is produced exits reactor 110 via gas line 117. This gas stream maycomprise unreacted alkylene oxides, for example. The reaction gasremoved via line 117 may be further treated, and the components may berecycled, as desired.

The reaction product stream including unconverted alkylene oxides andcorresponding byproducts exits (e.g. di- and polyglycols, dialkyleneglycol, trialkylene glycol and tetra-alkylene glycol) vessel 110 by wayof line 116. The alkylene glycol product may be recovered and treated asknown to those of skill in the art.

Production of Polyethylene Glycol (PEG)

In some embodiments, hydration of ethylene oxides leads to theproduction of polyethylene glycols (PEG's). In an embodiment, PEG's areproduced by reacting ethylene oxide with water. In another embodiment,PEG's are produced by reacting ethylene oxide with ethylene glycol. Inyet another embodiment, PEG's are produced by reacting ethylene oxidewith ethylene glycol oligomers. In some embodiments, ethylene glycol orethylene glycol oligomers are used as a starting material instead ofwater, because it allows the production PEG's with a low polydispersity.Such reactions are catalyzed by acidic or basic catalysts, such asmagnesium-, aluminium- or calcium-organoelement compounds, and alkalicatalysts (sodium hydroxide, potassium hydroxide, or sodium carbonate).

In an embodiment, feed streams of ethylene oxide and water or ethyleneglycol or ethylene glycol oligomers are intimately mixed in HSD 140(FIG. 1). Effluent 118 from HSD 140 is introduced into a fixed orfluidized bed 142 comprising a catalyst that promotes the formation ofPEG. In some cases, catalyst slurry is used and such slurry isintroduced into vessel 110 via line 115 together with effluent 119 frombed reactor 142. In some other cases, bed reactor 142 is omitted andcatalyst slurry and effluent 118 from HSD 140 are introduced intovessel/reactor 110. The production of PEG takes place under the actionof suitable catalysts. Due to the exothermic nature of the reaction,cooling systems are provided for bed reactor 142 and/or vessel 110 toprevent runaway polymerization reactions. In some embodiments, theproduced PEG is recovered from effluent 116 from vessel 110. In someembodiments, effluent 116 from vessel 110 is recycled to HSD 140 forfurther processing.

In an embodiment, feed streams of ethylene oxide and water (or ethyleneglycol or ethylene glycol oligomers) are introduced into HSD, whereinsaid HSD comprises a catalytic surface that promotes the formation ofPEG's. In another embodiment, catalyst slurry and feed streams ofethylene oxide and water (or ethylene glycol or ethylene glycololigomers) are introduced into HSD. The production of PEG's takes placein HSD under the action of the catalyst. In some cases, a cooling systemis provided to HSD to prevent runaway polymerization reactions. In someembodiments, the effluent from HSD is recycled as feed to HSD forfurther processing. In some other embodiments, the effluent from HSD isintroduced into a second HSD to further produce PEG's.

Multiple Pass Operation

In the embodiment shown in FIG. 1, the system is configured for singlepass operation, wherein the output from vessel 110 goes directly tofurther processing for recovery of alkylene glycol product. In someembodiments it may be desirable to pass the contents of vessel 110, or aliquid fraction containing unreacted alkylene oxide, through HSD 140during a second pass. In this case, line 116 is connected to line 121via dotted line 120, and the recycle stream from vessel 110 is pumped bypump 105 into line 113 and thence into HSD 140. Additional alkyleneoxide gas may be injected via line 122 into line 113, or it may be addeddirectly into the high shear device (not shown).

Multiple High Shear Devices

In some embodiments, two or more high shear devices like HSD 140, orconfigured differently, are aligned in series, and are used to furtherenhance the reaction. Their operation may be in either batch orcontinuous mode. In some instances in which a single pass or “oncethrough” process is desired, the use of multiple high shear devices inseries may also be advantageous. In some embodiments where multiple highshear devices are operated in series, vessel 110 may be omitted. In someembodiments, multiple high shear devices 140 are operated in parallel,and the outlet dispersions therefrom are introduced into one or morevessel 110.

While embodiments of the invention have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations. Use of broader terms such as comprises, includes,having, etc. should be understood to provide support for narrower termssuch as consisting of, consisting essentially of, comprisedsubstantially of, and the like. Accordingly, the scope of protection isnot limited by the description set out above but is only limited by theclaims which follow, that scope including all equivalents of the subjectmatter of the claims. Each and every original claim is incorporated intothe specification as an embodiment of the invention. Thus, the claimsare a further description and are an addition to the preferredembodiments of the present invention. The disclosures of all patents,patent applications, and publications cited herein are herebyincorporated by reference, to the extent they provide exemplary,procedural or other details supplementary to those set forth herein.

What is claimed is:
 1. A method of hydrating an alkylene oxidecomprising: introducing an alkylene oxide into water to form a firststream; flowing the first stream through a high shear device to producea second stream; and contacting the second stream with a catalyst in areactor to hydrate the alkylene oxide and form an alkylene glycol. 2.The method of claim 1, wherein the alkylene oxide is selected from thegroup consisting of ethylene oxide, propylene oxide, butylene oxide, andcombinations thereof.
 3. The method of claim 1, the method furthercomprising operating the high shear device at a tip speed of at leastabout 23 m/sec.
 4. The method of claim 1, the method further comprisingoperating the high shear device at a shear rate of greater than about20,000 s⁻¹.
 5. The method of claim 1, wherein producing the secondstream comprises an energy expenditure by the high shear device of atleast about 1000 W/m³.
 6. The method of claim 1, wherein the catalyst isselected from the group consisting of an amine, an acid catalyst, anorganometallic compound, an alkali metal halide, a quaternary ammoniumhalide, zeolites, and combinations thereof.
 7. The method of claim 1,wherein the alkylene glycol comprises ethylene glycol.
 8. A method ofhydrating an alkylene oxide comprising: introducing an alkylene oxideinto water to form a first stream; flowing the first stream through ahigh shear device to produce a second stream comprising high sheartreated alkylene oxide; and contacting the second stream with a catalystin a reactor to hydrate at least a portion of the high shear treatedalkylene oxide.
 9. The method of claim 8, wherein by way of contact withthe catalyst the portion of the high shear treated alkylene oxide formsalkylene.
 10. The method of claim 8, wherein in the reactor the alkyleneoxide is hydrated to form ethylene glycol.
 11. The method of claim 8,wherein the reactor is a fixed bed reactor, and wherein the catalyst isa hydration catalyst.
 12. The method of claim 8, the method furthercomprising operating the high shear device at a shear rate in the rangeof about 20,000 s⁻¹ to about 1,600,000 s⁻¹.
 13. A method of producingpolyethylene glycol comprising: introducing a first component comprisingethylene oxide and a second component selected from the group consistingof water, ethylene glycol, and ethylene glycol oligomer, into a highshear device to produce a first stream; and reacting at least a portionof the first stream with a catalyst to produce polyethylene glycol. 14.The method of claim 13, wherein the high shear device comprises acatalytic surface that promotes formation of polyethylene glycol. 15.The method of claim 13, wherein the reacting step occurs in a fixed bedreactor.
 16. The method of claim 13, the method further comprisingoperating the high shear device at a shear rate in the range of about20,000 s⁻¹ to about 1,600,000 s⁻¹.
 17. The method of claim 16, whereinthe high shear device comprises a catalytic surface.